Stitch control mechanism for sewing machines with combined lower and upper feed



g- 1965 R. REEBER STITCH CONTROL MECHANISM FOR SEWING MACHINES WITH COMBINED LOWER AND UPPER FEED Flled July 17. 1963 INVENTOR.

BY mm A T TOR/v6 Y United States Patent 3,198,154 SI'iTCH CUNTRUL MECHANISM FOR SEWKNG MACHINES WiTH QGMBHNED LGWER AND UPPER FEED Rudolf Reeber, Neuieefer Loin uber Munich, Germany,

assignor to G. M. Pfaif AG, Kaiserslantern, lifaiz, Germany, a corporation of Germany Filed July 17, B63, Ser. No. 295,758 Claims priority, application Germany, July 18, 1962, P 29,852 9 Claims. (Cl. 112--21tl) The present invention relates to stitch control for sewing machines equipped with combined lower and upper work feed means, and more particularly, though not limitatively, to work feeding arrangements comprising a lower feed dog or the like and a needle oscillated in the work feeding direction in synchronism with said feed dog, to act as upper feed means in a manner well known.

More specifically, the invention is concerned with the provision of improved feed stroke control means for machines of the type referred to embodying uni-control and adjusting means for the simultaneous variation of the operating stroke of both said lower and upper feed means and, in turn, of the stitches sewn by the needle in cooperation with a suitable loop taker.

It has been customary heretofore, in an effort to reduce to a minimum the moving masses in machines having an oscillating needle as a work feeding means, to mount the control mechanism for adjusting the needle oscillating amplitude in the direct vicinity of the needle or its oscillating frame or support, that is, in or upon the head and/or the adjoining part of the upper arm of a machine of conventional construction. Stitch control mechanism of this type has the drawback, among others, of occupying an undue amount of space at the very place or location ordinarily required for the mounting of accessory devices or auxiliary sewing aids. Besides, in arrangements of this type, oscillations or vibrations of the machine caused by the eccentric drive and the oscillating masses of the stitch control mechanism may be amplified or accentuated by reason of their increased distance from the center of gravity of the machine located in the upright section of the machine housing or opposite to the sewing head. This, in turn, greatly reduces or limits the operating or sewing speed, a serious drawback especially felt in the case of highspeed industrial or automated sewing machines.

Accordingly, among the objects of the present invention is the provision of stitch control mechanism for adjusting the feed stroke of a sewing machine of the type referred to and equipped with lower and upper feed means, whereby the prior and related difficulties and drawbacks are substantially overcome; which mechanism will fulfill the highest demands encountered in connection with modern industrial sewing operation; which mechanism, in particular its part for the control of the needle oscillations, has the advantage of easy and ready accessibility, to facilitate assembly, lubrication, as Well as adjustment and repairs or the like operations; and which is both simple in construction as well as efficient in operation, and can be readily embodied in conventional lower and upper feed type sewing machines.

The invention, both as to the foregoing and its ancillary objects as well as novel objects, will be better understood from the following detailed description of a preferred practical embodiment, taken in conjunction with the accompanying drawing forming part of this specification and in which:

FIG. 1 is a longitudinal cross-section through a sewing machine having lower and upper work feed means and embodying stitch control mechanism constructed 3,198,154 Fatented Aug. 3, 1965 "ice in accordance with the principles of the invention; and

PEG. 2 is an expanded and enlarged perspective view showing in greater detail the essential parts of the stitch control mechanism of the invention.

Like reference numerals denote like parts in both views of the drawing.

With the foregoing objects in view, the invention, according to one form of carrying the same into effect, involves generally the provision in a sewing machine of the type referred to and having a base plate, a housing comprised of an upright at one end of said plate and an overhanging arm extending from said upright in a direction parallel to said plate and terminating in a sewing head, and stitching tool means including a reciprocating needle mounted Within said head and a loop taker below said plate to produce stitches in a work piece fed along said plate, of work feed and stitch control means comprising lower and upper work feeding means supported by said head and said plate, respectively, a first drive shaft mounted within said arm which may be the main drive or arm shaft operating the needle for reciprocation in the vertical direction, and a first rockshaft also mounted within said arm parallel to said drive shaft and operably connected to said upper feed means, to intermittently engage and advance the work in synchronism with the stitching operation. According to one embodiment, as shown by the drawing, the upper feed means may consist in the needle frame or support being oscillated in the work feeding direction in synchronism with a feed dog or the like lower work feeding means, whereby the needle acts as the upper feed means in a manner well known. Alternatively, a Separate upper feed dog or the like feed means may be provided synchronized with the lower feed means and controlled by mechanism according to the invention, as will become further apparent as the following description proceeds.

There is furthermore provided in accordance with the invention a second drive shaft being in driving connection with said first drive shaft and mounted below the work supporting plate of the machine, said second drive shaft being advantageously constituted by the loop taker drive shaft for the operation of a loop taker in synchronism with the needle, in a manner Well known to those skilled in the art. There is further provided a second rockshaft also mounted below said plate parallel to said second drive shaft and operably connected to the lower work feed means, to intermittently engage the work in synchronism with the upper feed means. Finally, the invention embodies unitary stitch control means for adjusting the feed advance stroke of both said upper and lower feed means and including essentially first motion transrnitting mechanism operatively connecting said first drive shaft with said first rockshaft, to transmit rotary motion of said first drive shaft into oscillating motion of said first rockshaft for the operation of said upper feed means, second motion-transmitting mechanism operably connecting said second drive shaft with said second rockshaft, to transmit rotary motion of said second drive shaft into oscillating motion of said second rockshaft for the operation of said lower feed means, a first rotary control shaft operably embodied in said first mechanism for adjusting the oscillating amplitude of said first rockshaft and, in turn, the feed stroke of the upper feed means, a second rotary control shaft operably embodied in said second mechanism for adjusting the oscillating amplitude of said second rockshaft and, in turn, the feed stroke of said lower feed means, and uni-control means to commonly adjust both said control shafts for varying the feed strokes of both feed means or the stitching length, respectively.

According to a preferred embodiment, the uni-control means in the form of an adjusting knob or disk is mounted upon the outside of the upright of the sewing machine housing below the usual hand or flywheel of the machine and connected with both said control shafts through suitable motion transmitting linkage devices. As a consequence, the drawbacks and defects, in particular the problems of vibration, inherent in the prior stitch control arrangements are substantially eliminated or minimized by the invention while at the same time allowing of ready access to the control mechanism or parts thereof.

The motion-transmitting mechanism connecting the respective drive and rockshafts advantageously may consist of an eccentric having an eccentric rod, a lever having a pivot atone end and having its opposite end pivotally or rotatively connected to the end of said eccentric rod, to form a knuckle joint, means to. transmit oscillating motion of said lever to the rockshaft operating the respective feed means,.and means to vary the position of said pivot by the associated control shaft, to thereby control the amplitude of the oscillating motion transmitted to said shaft, in a manner'as will become further apparent from the following detailed description of the drawing;

The arm or drive shaft 2 mounted in the'upper arm of thehousing 1 of a'conventional sewing machine serves to reciprocate, by way of a crank 3 and link 4, the needle bar 5 carrying a' needle, said bar being mounted ina frame or support 7 rotatablysupported or journalled upon a stationary pin or pivot 6, to cause the needle to oscillate in the work feeding direction and to act as upper work feeding means in conjunction with a lower feed dog'or the like feed means 12. The armshaft 2 drives the loop taker shaft 9, mounted below the base or work-supporting plate of the machine, through a chain or the like trans-,

control mechanism 10 for adjusting the oscillating ampli- I tude of the needle supporting frame 7 and to control the upper feed stroke, and a second similar control mechanism 11 for adjusting the feed strokeof the feed dog 12, mechanism 10 being advantageously disposed upon the outside of the housing 1 or of the upright section of the latter and below the handor flywheel 13 and being sup: ported by a control shaft 14 journalled in said housing and extendingparallel to the main drive shaft2. C

In the following, there will be at first described the 7 construction of'the control mechanism 10. Secured tothecontrol shaft 14 is a first U-shaped member 15 between the arms 15a and 15b of which there is rotatively supported, by a pair of pins 17 and 17a, a further U-shaped member 16 having arms 16a and 16b which are connected by a I shaft or spindle 18 to which is imparted, by Way of an eccentric 19 and eccentric rod 20, oscillating motionfrom the drive shaft 2 with the pins 17 and 17a acting as rotating axis. 1

A link 21 having one end engaging the spindle 18 has its opposite end rotatively connected to aicr'ank 23 through a pin'22, said crank being in turn secured to a rockshaft 24- parallel to the shaft 2 and journalled in and extending outwardly fromthe housing. The opposite end'of the shaft 24 is connected to a further crank 25 which is, V in turn, operably connected to the oscillating needle frame,

.7 through a link 26, to transmit oscillating motion by said shaft to the needle bar 5.

The control mechanism llifor the feed dog 12 is con nected by way of a crank 28 to a control shaft 29 being .parallel to the loop taker drive shaft 9 and journalled in the housing 1. Secured to the free'end of the crank 28 is a pin' 30 upon which is rotatively mounted a lever arm 31' which is in operative connection, by way of a shaft or spindle 32, a further lever arm 33, pin 34 and a crank 35, witha rockshaft 36 also journalled in the housing 1 and being parallel to the loop taker drive shaft 9. Rockshaft 36 carries an oscillating member 37 to which is linked the feed dog 12, to operate the latter by the oscillating movements of the lever 31, in the manner further understood from the following. The control and motiontransmitting mechanism 11 is driven by the looptaker shaft 9 through an eccentric '38 and eccentric rod 39, the latter rotatively engaging the spindle 32 in a manner substantially analogous to the corresponding parts of the control mechanism 10 for the upper feed means, to convert rotary motion of the shaft 9 into oscillating motion of the shaft 36 for the intermittent operation of the feed dog 12 in synchronism with the needle operating means orframe7. r

The control shaft 14v of the motion-transmitting and control mechanism 10 is connected through a crank 40 and link 41 with a further crank 42 which is mounted uponthe'control shaft 29 of they mechanism 11, crank 42 being in turn connected, through a link 43 and a pair of ball or universaljoints 43a and 43b, with one end of a double-arm lever 44 rotatable about a stationaryshaft or axis 45 supported-by the housing 1. The opposite arm of the lever. 44'engages the cam-shaped groove 46a of an adjusting knob or disk 46 rotatively mounted upon the outsideof the upright section of thehousing 1.

Encirclingthe shaft 29 is a coil spring 47 having one end fixedly connected to the housing 1 and having its opposite end engaging or connected to said shaft, whereby to'urge both the control shafts 14 and 29 in the direction of forward feed of the workpiece being operated on. In order to reverse the feeding or stitching direction, there may be provided a control key 48-secured to the end of the shaft 45 projecting outwardly of the housing 1.

, The'mechanism 10, mounted substantially outside of the housing 1, is advantageously. protected by a-cover 49 which may also serve to conceal part of the hand wheel 11': and'of the control knob or disk 46, except for a relatively small adjusting aperture. j

In operation, both control mechanisms 10 and,11 are adjusted by the common or uni-control adjusting knob 46, being set to a predetermined position correspond- .ing to a desired stitching length, whereby to rotate the .control shaft 29 by the action of the spring 47 until the lever 44 engagestheedge of the groove 46a acting as an abutment therefor. Rotation of the shaft 29 further results in the rotation of the crank 28, whereby to displace. the pin'30, acting'as pivot or rotating axis of the lever 31,'relative to'the pinv 34. In the position shown .with both said pins 30 and 34 aligned along a common axis, the lever33 has no component ofmovement in the lengthwise direction, whereby no oscillating motion .will be imparted to the rockshaft 360i the feed dog 12; This adjustingposition corresponds, therefore, to

.the rest'or zero feed condition of the machine; On

the other hand, with the pin 30 serving as a pivot for the lever '31 being displaced relative to'the pin, 34 by the adjustment ofthe control shaft 29 through the ad- ,justing' knob 46, the spindle-.32 being actuated by the eccentric rod 39 causes the lever 31 to carryout a rotating motion about the pivot 30, :in such a manner as to impart to the lever 33, in addition to said rotary motion, a translatory motion or motion in its lengthwise direction. This latter motion is transmitted by means of thecrank 35 to the rockshaft 36 and oscillating member 37, to operate the'feed -.dog 12. The feed stroke is determined by the. amount of rotation of the control fshaft29, or extent .of relative displacement of the pins 30 and 34,: whereby *to enable". a gradual feed stroke control between zero and a'maximum by rotation of the knob or disk 46.

Rotation of the control shaft 29 by the knob 46 also causes a corresponding rotation of the control shaft 14 ofthe needle oscillation control mechanism IO by way of the crank 42, connecting link "41 and crank 40. As a consequence, arins'lSw' and 15b of the member 15 being secured to the shaft "14 cause a rotation of the arms 16aand 16b of the member 16, whereby to displace the pins 17 and 17a, forming the rotating axis of the member 16, relative to the spindle 22. Accordingly, the arms 16a and 16b, in analogy to the correspending parts of the mechanism 11, carry out a pure rotating motion about the pins 17 and 17a as a result of the oscillations of the spindle l8 imparted thereto by the eccentric rod 2t). Link 21, aside from this rotary motion, is subjected to a translatory motion, whereby to result in an oscillating motion of the crank 23 and, in turn, of the crank 25 connected to the needle oscillating frame 7 through the rockshaft 24. As a consequence, the oscillating motion of shaft 25 is transmitted by the link 26 connected to the crank 2%? to the needle frame 7, whereby with the proper design of the mechanisms llti and 11 the needle will be oscillated in the feeding direction in synchronism and cooperation with the feed dog 12 for any feed stroke adjustment effected by the control of the knob 4-6.

In the foregoing the invention has been described in reference to a specific illustrative device. It will be evident, however, that variations and modifications, as Well as the substitution of equivalent parts and elements for those shown herein for exemplification may be made without departing from the broader scope and spirit of the invention as set forth in the appended claims. The specification and drawing are accordingly to be regarded in an illustrative rather than in a restrictive sense.

I claim:

1. In a sewing machine of the type having a base plate, a housing including an upright and an overhanging arm extending therefrom in a direction parallel to said plate and terminating in a sewing head, a reciprocatory needle mounted within said head, to produce stitches in a workpiece fed along said plate, a needle drive shaft within said arm operably connected to said needle, to reciprocate said needle in the vertical direction, and a loop taker drive shaft in driving connection with said first drive shaft and mounted below said plate; work feeding means comprising in combination:

(1) a first rockshaft mounted within said arm and operably connected with said needle, to oscillate the same in the work feeding direction, to provide first work feeding means of said machine,

(2) a work feeding dog,

(3) a second rockshaft mounted below said plate and operably connected to said dog, to provide second work feeding means of said machine, and

(4) drive and unitary stitch control means to operate said first and second rockshaft and to adjust the feed advance strokes of both said work feeding means, comprising:

(a) first motion-transmitting mechanism operably connecting said needle drive shaft with said first rockshaft, to convert rotary motion of the needle drive shaft into oscillating motion of said first rockshaft,

(b) second motion-transmitting mechanism operably connecting said loop taker drive shaft with said second rockshaft, to convert rotary motion of said loop taker shaft into oscillating motion of said second rockshaft,

(c) a first rotary control shaft of said first mechanism operative to control the feed stroke of said needle in accordance with the angular adjusting position of said first control shaft,

((1) a second rotary control shaft of said second mechanism operative to control the feed stroke of said dog in accordance with the angular adjusting position of said second control shaft, and

(e) uni-control means to adjust both said control shafts, to simultaneously vary the feed strokes of said needle and feed dog in synchronism.

2. In stitch control mechanism for a sewing machine with lower and upper work feed as claimed in claim 1, said unitary controlmeans comprising an adjusting knob and motion transmitting linkage means connecting said knob with both said control shafts.

3. In stitch control mechanism for a sewing machine with lower and upper work feed as claimed in claim 2, said machine having a flywheel disposed upon the end of said needle drive shaft projecting outwardly from said upright, and said adjusting knob being disposed upon the outside of said upright underneath said flywheel.

4. In a sewing machine of the type having a base plate, a housing including an upright and an overhanging arm extending therefrom in a direction parallel to said plate and terminating in a sewing head, a reciprocatory needle mounted in said head, a first drive shaft mounted in said arm and operably connected with said needle, and work feeding means to intermittently advance a workpiece along said table for cooperation with said needle and a. loop taker to form stitches, said feeding means comprising in combination:

(1) upper work feeding means mounted upon said head,

(2) lower work feeding means mounted below said plate,

(3) a second drive shaft in driving connection with said first drive shaft and mounted below said plate,

(4) a first rockshaft mounted within said arm and operably connected with said upper work feeding means,

(5) a second rockshaft mounted below said plate and operably connected with said lower work feeding means, and

(6) drive and unitary stitch control means to operate said first and second rockshafts and to adjust the feed advance strokes of both said work feeding means comprising:

(a) first motion-transmitting mechanism operably connecting said first drive shaft with said first rockshaft, to convert rotary motion of said first drive shaft into oscillating motion of said first rockshaft,

(b) second motion-transmitting mechanism operably connecting said second drive shaft with said second rockshaft, to convert rotary motion of said second drive shaft into oscillating motion of said second rockshaft,

(c) a first rotary control shaft of said first mechanism operative to control the feed stroke of said upper feeding means in accordance with the angular adjusting position of said first control shaft,

(d) a second rotary control shaft of said second mechanism operative to control the feed stroke of said lower feeding means in accordance with the angular adjusting position of said second control shaft, and

(e) uni-control means to adjust both said control shafts, to simultaneously vary the feed strokes of said upper and lower feed means in synchronism.

5. In stitch control mechanism for a sewing machine with lower and upper work feed as claimed in claim 4, said unitary control means comprising an adjusting knob and separate motion-transmitting linkage means connecting said knob with both said control shafts.

6. In stitch control mechanism for a sewing machine with lower and upper work feed as claimed in claim 5, said first drive shaft carrying a flywheel at its end projecting outwardly from said upright, and said adjusting knob being disposed upon the outside of said upright underneath said flywheel.

'7. In stitch control mechanism for a sewing machine with lower and upper work feed as claimed in claim 4, said unitary control means comprising an adjusting knob having a cam, motion transmitting linkage means having an input element operablyengagedby said cam and having a pair of output elements each arranged,- respectively, to actuate one of said control shafts;

8. In stitch control mechanism fora sewing machine with lower and upperwork feed as claimed-in claim 4, each said first and 'second motion-transmitting mechanism comprising an eccentric rod connected to an eccentric mounted upon the associated drive shaft, a first lever having a normally stationary first pivot at one end and having its opposite end rotatively connected to the end of said rod, a second lever having a pivot atone end connected'to the associated rockshaft and-having its opposite end rotatively connected to the endof said rod,-

and means to adjust the position of said first pivot by the associated control shaft, to vary the amplitude of the oscillations transmitted to said rockshaft.

9. In a sewing machine of the type including stitchforming means, a first drive shaft operably connected to (2) a first rockshaft operably connected to said first device, to intermittently engage and advance the work operated on,

(3) a second feeding device, a

(4) a second rockshaft' operably connected to said second feeding device, to intermittently engage and advance the work in synchronism with said first device, and

(5) drive and unitary stitch control means to operate said rockshafts and to adjust the feed advance strokes of both said devices comprising:

(a) 'first motion-transmitting mechanism operably connecting said first drive shaft with said first rockshaft, to convertrotating motion of said first drive shaft into oscillating motion of said first rockshaft,

(b), a second drive shaft in driving connection with said first drive shaft,

(0) second motion-transmitting mechanism operably connecting said second drive shaft: with said second rockshaft, to convert rotary motion of said second drive shaftinto oscillating motion of said second rockshaft,

(d) a first rotary control shaft of said first mech anism operative to control the feed stroke of said first device in accordance with the angular adjusting position of said first control shaft,

(e) a second rotary control shaft of said second mechanism operative to control the feed stroke of said second device in accordance withthe angular adjusting position of said second convtrol shaft, and I. I

(f) uni-control means to adjust both said control shafts, to simultaneously vary the feed strokes of said devices in synchronism.

References Cited by the Examiner UNITED STATES PATENTS 804,220 11/05 Gray 112 213 860,733 7/07 Cummings l12213 929,761 8/09 Gray 1l'2213 1,685,436 9/28 Ringe ll2-208 2,329,484 9/43 QuiSt l12206 JORDAN FRANKLIN, Primary Examiner. 

1. IN A SEWING MACHINE OF THE TYPE HAVING A BASE PLATE, A HOUSING INCLUDING AN UPRIGHT AND AN OVERHANGING ARM EXTENDING THEREFROM IN A DIRECTION PARALLEL TO SAID PLATE AND TERMINATING IN A SEWING HEAD, A RECIPROCATORY NEEDLE MOUNTED WITHIN SAID HEAD, TO PRODUCE STITCHES IN A WORKPIECE FED ALONG SAID PLATE, A NEEDLE DRIVE SHAFT WITHIN SAID ARM OPERABLY CONNECTED TO SAID NEEDLE, TO RECIPROCATE SAID NEEDLE IN THE VERTICAL DIRECTION, AND A LOOP TAKER DRIVE SHAFT IN DRIVING CONNECTION WITH SAID FIRST DRIVE SHAFT AND MOUNTED BELOW SAID PLATE; WORK FEEDING MEANS COMPRISING IN COMBINATION: (1) A FIRST ROCKSHAFT MOUNTED WITHIN SAID ARM AND OPERABLY CONNECTED WITH SAID NEEDLE, TO OSCILLATE THE SAME IN THE WORK FEEDING DIRECTION, TO PROVIDE FIRST WORK FEEDING MEANS OF SAID MACHINE, (2) A WORK FEEDING DOG, (3) A SECOND ROCKSHAFT MOUNTED BELOW SAID PLATE AND OPERABLY CONNECTED TO SAID DOG, TO PROVIDE SECOND WORK FEEDING MEANS OF SAID MACHINE, AND (4) DRIVE AND UNITARY STITCH CONTROL MEANS TO OPERATE SAID FIRST AND SECOND ROCKSHAFT AND TO ADJUST THE FEED ADVANCE STROKES OF BOTH SAID WORK FEEDING MEANS, COMPRISING: (A) FIRST MOTION-TRANSMITTING MECHANISM OPERABLY CONNECTING SAID NEEDLE DRIVE SHAFT WITH SAID FIRST ROCKSHAFT, TO CONVERT ROTARY MOTION OF THE NEEDLE DRIVE SHAFT INTO OSCILLATING MOTION OF SAID FIRST ROCKSHAFT, (B) SECOND MOTION-TRANSMITTING MECHANISM OPERABLY CONNECTING SAID LOOP TAKER DRIVER SHAFT WITH SAID SECOND ROCKSHAFT, TO CONVERT ROTARY MOTION OF SAID LOOP TAKER SHAFT INTO OSCILLATING MOTION OF SAID SECOND ROCKSHAFT, (C) A FIRST ROTARY CONTROL SHAFT OF SAID FIRST MECHANISM OPERATIVE TO CONTROL THE FEED STROKE OF SAID NEEDLE IN ACCORDANCE WITH THE ANGULAR ADJUSTING POSITION OF SAID FIRST CONTROL SHAFT, (D) A SECOND ROTARY CONTROL SHAFT OF SAID SECOND MECHANISM OPERATIVE TO CONTROL THE FEED STROKE OF SAID DOG IN ACCORDANCE WITH THE ANGULAR ADJUSTING POSITION OF SAID SECOND CONTROL SHAFT, AND (E) UNI-CONTROL MEANS TO ADJUST BOTH SAID CONTROL SHAFTS, TO SIMULTANEOUSLY VARY THE FEED STROKES OF SAID NEEDLE AND FEED DOG IN SYNCHRONISM. 